This invention relates to latexes having both pH independent and pH dependent bound charges on the surface of the latex particles. This invention also relates to fibrous composites made from such latexes.
In the preparation of latexes, it has become standard practice to employ agents to increase the colloidal stability of the polymer particles. Specifically, it has become a widely employed practice to include small amounts of an addition polymerizable carboxylic acid as a monomer in the latex polymerization. This acid functionality gives the latex increased colloidal stability over a wide pH range. In fact, latexes prepared in this manner are often so stable that intentionally destabilizing them becomes a very difficult task. Further, when such latexes are destabilized, usually by chemical flocculants, the flocculation takes place in a very uncontrolled manner. While some progress in the art of stabilization is taught, for instance, in U.S. Pat. No. 3,261,796 (Simms, 1966) and U.S. Pat. No. 3,637,565 (Sheetz, 1972), there is still a great deal of room for improvement in the field of latex stabilization.
In particular, it would be desirable to have latexes which are stable, but which may be readily and controllably destabilized by the user.